Authors' objectives:

1. To describe the diversity and reasons for diversity of available patient-based outcome measures

2. To make clear the criteria investigators should have in mind when they select patient-based outcome measures for inclusion in a clinical trial.

Authors' results and conclusions: Diversity of patient-based outcome measures Seven major types of instrument can be identified in the literature: disease-specific, site-specific, dimension-specific, generic, summary item, individualised, utility. Concepts, definitions and theories of what such instruments measure are generally not clearly or consistently used. For example, there is little consistency of use or agreement as to the meaning of key terms such 'quality of life' and health-related quality of life'. The intended purpose and content of types of instruments vary. There are advantages and disadvantages to each of the different type of instrument when used in a particular clinical trial. Criteria for selecting patient-based outcome measures There are eight criteria that investigators should apply to evaluate candidate patient-based outcome measures for any specific clinical trial: appropriateness, reliability, validity, responsiveness, precision, interpretability, acceptability, feasibility. These criteria are not consistently defined and the literature associated with the criteria cannot be summarised in clear, explicit and unambiguous terms. It is not possible from available evidence to rank order the relative importance of the eight criteria in relation to decisions about selection of measures to include in a trial. Appropriateness requires that investigators consider the match of an instrument to the specific purpose and questions of a trial. Reliability requires that an instrument is reproducible and internally consistent. Validity is involved in judging whether an instrument measures what it purports to measure. Responsiveness in this context addresses whether an instrument is sensitive to changes of importance to patients. Precision is concerned with the number and accuracy of distinctions made by an instrument. Interpretability is concerned with how meaningful are the scores from an instrument. Acceptability addresses how acceptable is an instrument for respondents to complete. Feasibility is concerned with the extent of effort, burden and disruption to staff and clinical care arising from use of an instrument.

Authors' recommendations: Investigators need to make their choice of patient-based outcome measures for trials in terms of the criteria identified in this review. Developers of instruments need to make available evidence under the same headings. By means of the above criteria, further primary research and consensus-type processes should be used to evaluate leading instruments in the different fields and specialties of health care to improve use of patient-based outcome measures in trials. Primary research is needed either in the form of methodological additions to substantive clinical trials (for example comparing the performance of two or more measures) or studies of leading measures with methodology as the primary rationale.

Authors' methods: Review

Project Status: Completed

URL for project: http://www.hta.ac.uk/934

Year Published: 1998

English language abstract: An English language summary is available

Publication Type: Not Assigned

Country: England, United Kingdom

Organisation Name: NIHR Health Technology Assessment programme

Contact Address: NIHR Journals Library, National Institute for Health and Care Research, Evaluation, Trials and Studies Coordinating Centre, Alpha House, University of Southampton Science Park, Southampton SO16 7NS, UK

Contact Name: journals.library@nihr.ac.uk

Contact Email: journals.library@nihr.ac.uk

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